code: def test_average_prefix_tuning(self):
      model = self.get_model()
      self.run_average_test(
          model,
          PrefixTuningConfig(flat=True),
          ["prefix_tunings.{name}."],
      )
  
file_path: adapters/tests/methods/test_prefix_tuning.py
imports: import torch
  from adapters import ADAPTER_MODEL_MAPPING, AutoAdapterModel, PrefixTuningConfig
  from transformers import CLIPConfig
  from transformers.testing_utils import require_torch, torch_device
  from .base import AdapterMethodBaseTestMixin
label_desc: Use image node_id 3 for calling the PrefixTuningTestMixin obj's underlying member method code with example usage: obj.test_average_prefix_tuning() without return types